34 Experiments upon Gunpowder. 



and are much flattened ; and bullets from muskets are 

 always found to be hotter in proportion to the hardness 

 of the body against which they are fired. If a musket- 

 ball be fired into a very soft body, as (for instance) 

 into water, it will not be found to be sensibly warmed; 

 but if it is fired against a thick plate of iron, or any 

 other body that it cannot penetrate, the bullet will be 

 demolished by the blow, and the pieces of it that are 

 dispersed about will be found to be in a state very little 

 short of fusion, as I have often found by experience. 

 It is not by the flame, therefore, that bullets are heated, 

 but by percussion. They may indeed receive some 

 small degree of warmth from the flame, and still more 

 perhaps by friction against the sides of the bore, but it 

 is in striking against hard bodies, and from the resist- 

 ance they meet with in penetrating those that are softer, 

 that they acquire by far the greater part of the heat we 

 find in them as soon as they come to be at rest, after 

 having been discharged from a gun. 



There is another circumstance that may possibly be 

 brought as an objection to this opinion, and that is, 

 the running of the metal in brass guns upon repeat- 

 edly firing them, by which means the vent is often so 

 far enlarged as to render the piece intirely useless. But 

 this, I think, proves nothing but that brass is very 

 easily corroded and destroyed by the flame of the gun- 

 powder ; for it cannot be supposed that in these cases 

 the metal is ever fairly melted. The vent of a musket 

 is very soon enlarged by firing, and after a long course 

 of service, it is found necessary to stop it up with 

 a solid screw, through the center of which a new vent 

 is made of the proper dimensions. This operation is 

 called bushing, or rather bouching, the piece ; but in 



